According to NIH estimates in 2008, 30-50 million Americans are lactose intolerant” (the Food and Drug Administration's Consumer Health Information on the agency's website). In the 1960s and 1970s, it was reported that 70% of the adults in the world had lactose intolerance. In 1995, it was reported that 75% of the adults in the world and 25% of the adults in the U.S. were categorized as being lactose intolerant. In 1994, it was reported that 75% of African Americans and Native Americans and 90% of Asian Americans had lactose intolerance. It has also been reported that 30% of adults who are mostly North American descendants of Europeans have adapted to high lactase activity into adulthood. Research concludes that this adaptation is genetically controlled, permanent, and related to a long tradition of milk and milk product consumption in these regions of the world.
Lactose intolerance is the inability to digest significant amounts of lactose, a major natural sugar found in milk and milk products of all mammals. Lactose intolerance is caused by a shortage of the enzyme lactase, which is produced by the cells that line the small intestine and is essential to lactose digestion. Lactase breaks down lactose, a disaccharide, into two simpler forms of sugar called glucose and galactose, which are then transported across the cell membrane and absorbed into the bloodstream. If lactase is not present, or not present in sufficient levels, excess undigested lactose passes through the small intestines into the large intestine where it is fermented by bacteria in the colon (“colonic microbiota,” “gut microbiota,” “intestinal microbiota,” or “commensal gut microbiota”). The fermentation of lactose in the large intestine produces hydrogen and methane which can lead to bloating, gas, and diarrhea. These symptoms are caused by a very low activity of lactase in the intestines and are found in subjects who are lactose intolerant. Not all subjects deficient in lactase have the symptoms commonly associated with lactose intolerance, but those who do are said to have lactose intolerance.
This decrease in lactase activity results in a demonstrated maldigestion of the sugar lactose, either with or without symptoms, after ingesting dairy products such as milk, ice cream, cheese and pizza. Lactose maldigestion, with or without the symptoms commonly associated with lactose intolerance, is often defined more specifically as an “increase in blood glucose concentration of <1.12 mmol/L or breath hydrogen of >20 ppm after ingestion of 1 g/kg body weight or 50 g lactose” (de Vrese et al., 2001).
If a subject suspects that he or she has lactose intolerance, it is potentially harmful for him or her to restrict his or her diet because restriction can result in a nutrition shortage or a failure to detect a more serious disease. Milk and other dairy products are major sources for nutrition in the basic American diet. The primary nutrients in milk are protein, calcium, riboflavin, vitamin A, and vitamin D. Calcium is an important part of the recommended daily allowance of vitamins and minerals and any deficiency therein can lead to increased risk of osteoporosis and hypertension (McCarron and Heaney 2004) and possibly cancer (Barger-Lux and Heaney 1994; Consensus Conference: Optimal Calcium Intakes, NIH 1994).
Young children who have lactose intolerance are very rare. The amount of the enzyme lactase a body produces generally reaches a maximum immediately after birth and then decreases in the majority of people during the ages of about 3-15.
Generally, humans develop lactose intolerance from a primary or secondary cause. The primary cause is an onset of loss of lactase that is believed to be a permanent condition. This onset can occur at a variable period after the weaning period. The primary cause is also genetically determined. The secondary cause is generally a temporary condition that occurs as a result of another disease or event that damages the lining of the small intestine where lactase is active. This temporary condition can be caused by acute diarrhea, disease, parasitic infection, Cohn's disease, celiac disease, gastrointestinal surgery, or the intake of certain medications.
In addition to the primary and secondary causes, certain human ethnic and racial populations have more of a predisposition for lactose intolerance. In these populations, social and cultural habits and attitudes influence lactose intolerance. Lactose activity can also decrease with age in certain ethnic and racial populations, including those populations which have origins in Europe, the African plains, and the Siberian Steppes. Humans who are most likely to have or develop lactose intolerance include those of Asian, Middle Eastern, North American, African, and Latin American decent.
Currently, there is no universally accepted therapy for the treatment of lactose intolerance. As such, most lactose intolerant individuals avoid the ingestion of milk and dairy products, while others substitute non-lactose containing products in their diet. The avoidance of lactose makes the occurrence of symptoms more likely when dairy foods are consumed.
Nutritional supplements currently sold often offer no proven benefit or in some instances, must be ingested prior to eating dairy, where the outcome is dependent on the dose of the supplement and relative to the amount of lactose consumed. In some instances, use of a nutritional supplement to manage the symptoms associated with lactose intolerance may require large dosages, such as five or more pills per day.
There is need in the medical community for a tolerable and convenient treatment that allows for all levels of milk and dairy product consumption in people suffering from mild to severe lactose intolerance. A treatment that provides a simplified dosing regimen as well as the potential for extended relief from symptoms following a limited therapy regimen (e.g., <30 days) would result in greater compliance and address an unmet medical need.
“Prebiotics” are non-digestible food ingredients that stimulate the growth or activity of bacteria in the digestive system that are beneficial to the health of the body (Gibson and Roberfroid 1995). Typically, prebiotics are carbohydrates such as oligosaccharides, but the definition does not preclude non-carbohydrates.
Prebiotics have been further defined as fulfilling three criteria (Gibson et al. 2004):
1) Resistance to gastric acidity, hydrolysis by mammalian enzymes and gastrointestinal absorption;
2) Fermentation by intestinal microflora; and
3) Selective stimulation of the growth and/or selective activity of intestinal bacteria associated with health and well-being.
Substantial data exist to support the strategy that colonic bacteria adapt readily to undigested carbohydrates, resulting in dramatically improved lactose tolerance. A purified GOS preparation, can promote the selective growth of beneficial colonic bacteria, including multiple species and strains of bifidobacteria and lactobacilli. Bifidobacteria carry out non hydrogen-producing lactose fermentation reactions in addition to inhibiting hydrogen producing bacteria, such as Escherichia coli (E. coli). It is this excessive hydrogen production that defines lactose malabsorption and ultimately is responsible for the symptoms associated with lactose intolerance (Ballongue 1993; Gibson 1994, 1995). A recent study indicates that higher purity GOS formulations have a greater potential to selectively promote the growth of beneficial lactobacilli and bifidobacteria (Klaenhammer 2010).